I think it's controversial not because it's false, but because calorie density variation in food is huge, a full order of magnitude, so only reducing quantity i

I think it's controversial not because it's false, but because calorie density variation in food is huge, a full order of magnitude, so only reducing quantity is not the best strategy in most cases. 100g of fries is about 250kcal, 100g of cabbage is around 30 You can quite literally eat 10 times as much cabbage as fries to have the same amount of calories And eating less triggers a feeling of hunger (at least at the beginning), which makes following through harder.